Artificial leg



UNITED sTATEs TATENT ornion.

DOUGLAS BLY, OF ROCHESTER, NEW YORK.

ARTIFICIAL LEG.

Specification forming' part of Letters Patent No. 24,002, dated. May 17,1859; Reissued J'u1y 3, 1860,

To all whom 'it may concern:

Be it known that I, DOUGLAS BLY, of the city of Rochester, in the countyof Monroe, State of New York, have invented certain new and usefulImprovements in the Con* struction of Artificial Legs, of which thefollowing is afull and accurate description, reference being had to theaccompanying drawings, making a part of thesespecifications, and theletters of reference marked thereon, same letters referring to likeparts in all the figures.

Of said drawings, Figure l is a leg n sit/a. Fig. 2 is a verticalsection showing the mode of constructing the same. Fig. 3 1s the portionwhich forms Vthe ankle joint detached from the other parts. Fig. 4 is atransverse section of the box and bolt at knee-joint. Fig. 5 is alongitudinal section of the box, showing its relative position. Fig. 6is a view showing the manner of fastening the ends, and regulating thetension of the cords. Fig. 7 is a view of the curved metallic straps orbars used when amputation has taken place below the knee. v

Before proceeding to describe my articial leg as now constructed, Iwould state that I have only larrived at it, after a series of laboriousand expensive experiments.

The nature of this invention consists in a certain arrangement andcombination of parts, whereby a more perfect substitute is attained forthe natural leg: the action of the latter as provided for by variousmuscles, tendons and joints being simulated by simple substance, arerepresented in the accompanying drawings.

In ordinary walking, the power of moving the ankle joint in alldirections is necessary to ease and grace. Different portions of thefoot may be placed on little elevations or depressions in the ground, oron sticks and stones, which make it necessary that the ankle jointshould move more or less in all directions, so that the foot canaccommodate itself to the inequality of the surface. When walking, thetoes are turned outward, `so that the line of flexion of the ankle jointis not in a right line with the foot, but in a line with the ball of thegreat toe, which requires a diagonal flexion. By providing for this,

the fatiguing and uncouth halt, which is so often seen iny those wearingartificial legs is avoided.

It is necessary that the ankle joint should flex sidewise or laterallywhen an effort is made to lift a heavy weight, as the feet are thenspread far apart, and the le s are no longer perpendicular to the soleso the feet. Indeed, this is the case in almost all kindsof labor, as thefeet are then generally spread far apart to give a wide basis ofsupport, as seen in planing, filing, sawing, etc.

In the natural limb means are provided not Vonly for flexing the footVon the leg antero-posteriorly, but diagonally, as in ordinary walkingvwith the toes turned outward and sidewise or laterally, as in manypositions assumed in labor, or when one side of the foot is placed onelevations or depressions in the ground. I provide for all these motionsby constructing the ankle joint as follows The superior portion of thefoot is formed by a block, (A,) which represents the astragalus,(theupper bone of the foot.) Through this block a bolt` or pivot (B) passeslongitudinally, and takes bearings at each end, in solid portions of thefoot. This allows a free and easy lateral motion. Another bolt, or axis,(0,) passes through the same block transversely, the two ends of whichsupport the leg (D), and allow a free and easy antero posterior motion.These two motions combined, produce motion in all directions;consequently, every motion of the natural leg is provided for. Thesebolts or axes, also the one at the knee joint are made of vulcanizedY orhard india rubber, a substance, which, for this purpose, possesses threegreat advantages over all other substances known-First, extremelightness-Second, the nature of the material is such that very, very,littlerfriction takes place-Third, the nature of the n ticus muscles,the peronius tertius, `l'ongus l and brevis muscles, and thegastroc-ne1nius and soleus muscles, and their tendons.

The muscles are simulated by springs, (E) made of india rubber used bycompression. The advantages of rubber springs used in this manner aredecided and important. First, since they are used by compression, theycannot be overtaXed or broken. Second,-their actions are more uniform,soft, and easy, like the natural muscles. Third,-they never rust. neverrattle. Fifth-they require no oil. And the tendons Y are simulatedv bynonelastic cords (F) attached to the springs, these being keptsuiiciently tense to retain the foot in its normal position, in relationto the leg, while at the same time, by means of the oint abovedescribed, the foot may be moved in any required direction. The ends ofthe cords are secured, and their tension regulated by means of the screw(G) and nuts (I-I) which are constructed by cementing the cord into atube, which has a screw and nut on its outer surface. To insuresolidity, the end of the cord is enlarged by being doubled back uponitself and then trimmed to a conical form and the tube is made conicalto receive it.

The object in placing the cords and springs in positions correspondingwith those of the natural muscles, is to perfect the mechanicalarrangement, and steady the motions, since in order to securesteadiness, it is absolutely necessary that the foot be retained in itsnormal position, by two oppositeA yielding forces. In the natural limbthis is attained by the antagonistic muscles.

When amputation .has taken place below the knee joint, the knee of theartificial leg is formed by means of two jointed metallic straps or bars(J) one on each side. Each of these straps consists of an upper andlower section, which are connected by means of a mortise and tenonjoint, and moving upon the pivots or axes (K) the lower ends of theupper section, and the upper end of the lower section are curvedbackward so as to carry the joint or hinge back of a right line, andthereby simulate the shape of the bones of the natural leg, and obtain ajoint, which works in harmony with the natural one, which is animportant improvement. Furthermore, by means of this curve, the metallicstraps conform to the contour of the natural limb when it is flexed, andprevent the joints from pressing the parts forward in an unseemly mannerwhen sitting, and, from chang and cutting them. Furthermore, by means ofthis curve, I am able to increase the distance between the pivot, (K)and the anterior portions of the mortise and tenon which come in contactand form a stop to the oint, the benefit of which is twofold-increasedstability when standing, and less liability of the parts which come incontact to wear.

For amputations above the knee, Athe knee joint is formed` by means of avulcanized or hard india rubber bolt or axis, (P) which takes itsbearing in the superior portion of `the leg (D) and supports the thigh(L).

The bearing for this bolt is formed by means of two blocks, (N N) of anyvsuitable material, which pass through the upper part of the leg (D),each of which contains a longitudinal groove equal to a quarter circlemore or less, one of' these blocks being above, and the vother below thebolt. Abovethe upper part are two screws (S S.) which serve to press theupper block down upon the bolt, and thereby adjust and regulate thebearings. By forming the bearings in this manner two important resultsare obtained, viz :#First, the joint can be kept tight and all noiseprevented. No arrangement has ever been before, to my knowledge,introduced into the joints of artificial legs, by which the parts may beadjusted so as to compensate for the wear occasioned by use, and therebythe rattling prevented. Second, by thus reducing the bearing surface,the friction is reduced, which is of great importance when thepropelling power is so limited.

When the leg moves from a flexed to a straight position, the motion ofthe kneejoint is limited and controlled by means of the cord (T) andspring, (X) formed like those before described in this specication. Oneend of this cord is attached to the posterior superior portion of theleg, (D) and the other end, to a cross bar in the anterior inferiorportion of the thigh By placing the cord in this position, it is broughtnearly in line with the strain or draft, which enables it to control orlimit the motions of the joint with facility, and the spring preventsany jar which otherwise might arise from stopping the motion toosuddenly; it also prevents the appearance of sudden mechanical actionand renders it more like that of nature.

What I claim as new, and desire to secure by Letters-Patent, is

Vl. I claim curving or deflecting the j oint ed extremities of the bars,(J) so as to bring their axes of motion back of their line of direction,substantially as, and for, the purpose set forth.

2. I claim the cord (T) and sprin (X) acting upon the parts (D and L)vsustantially in the manner and for the purpose herein set forth. l

3. I am aware that metallic springs have been employed to simulate thefunctions of the natural muscles, but experience has proved theirinadequacy, both as respects the results obtained, and their durability.

am also aware that india rubber or elastic traction and expansion of thematerial, and cords have been used for the same purpose, not from itselongation and contraction, suband with no better results; and these Ido stantially as set forth.

not claim; but I claim the combination of DOUGLAS BLY. 5 the non-elastictendon (F) with the india Witnesses:

rubber spring (E,) in such a manner that J. FRASER,

the required eifect is derived from the con- S. J. ALLIs.

